Fluid fuel burner control apparatus



Marh 27, 1945.

S. G. ISSERSTEDT FLUID FUEL BURNER CONTROL APPARATUS Filed March 26,1945 attorney;

. timin meansioi' interposing 0mm VIII. BI. am

zsnare mum-m1. imam coN'raor. mans-ms Siegfried G. Isserstedt, Toronto,Ontario. Canada, ll lnor Gummy, Delaware tc MinneapolismoneyweilRegulator 7 Minneapolis,

Application March 26, 194:, Serb] s tsetse isolates.

The present invention is directed to automatic control apparatus for theburners of fluid fuel, and is more particularlyconoerned with apparatusfor that type'of system which incorporates separate timing means forplacing the system in operation, and for terminating operations! theignition means in the case oLan intermittent 1g- 'nition system. l

where an intermittent ignition system is desired, to time the postignition period followingthe es- 7 tablishment of combustion.

In systems where fluid rue is burned; and

' particularly where this fuel is oil, 1: is desirable to interpose acertain'predet'ermined minimum period of inaction between successiveenergizations or operations of the burner for the purpose of allowingthe vapors of unburned fuel .to pass out of the combustion chamber andup the stack.

sponsive to the presence or the absence oi combustion within thecombustion chamber. 7 Thus when operation of the burner is terminatedthe combustion responsive device will require a cer-' tain predeterminedtime to return to its cold.

position and the control system is'so arranged that the burner cannot bereenergized until such action has taken place.

tion however was designed to be used in'combination with a, combustionresponsive device which is extremely sensitive and which passes from its,hot to its cold position so rapidly that it cannot be used fortimingthe del'aybetween successive burner energizations. When such a com.bustion responsive device is used it is necessary to provide someadditional means for preventing the reenergization oi the burner until acertain predetermined minimum oi. time has elapsed.

In the case of intermittent ignition systems it has been the practice inmany prior art control 4 systems to time the post ignition period bymeans of the combustion responsive device. Thus upon the establishmentof combustion the combustion responsive device starts to heat and aftera certain length ct time will deenergize' the ignition.

Where an extremely sensitive combustion respon- 'sive device is. usedhowever, some] additional means-must beprovided for timing thepost'ignit'on period in view of the fact-that it is not desirable: todeenerslze the ignition device im-' mediatelyupcn the establishment ofcombustion.

11; is therefore a prime object of the present invention to design acontrol apparatus fora A further object of the-invention is to design a8 of the above type in which the timing means is energized upon a demandfor burner operation for producing the proper timing functions and isdeenergized during the normal operation of the burner. The above featureis parin the form oi a thermal timer in view of the is In many prior"art control systemsthis timing is obtainedqby means of a devicewhich isrea holding the safety switch in closed position, one

latches i4 and II system whichutiliaesanextremelysensitive combustionresponsive device and which has thermal energizations, and

fact that-where the thermal timer is heated during the entire time thatthe burner is in operaing the termination of burner operation.

A further object of the invention is to provide a control system havinga biased open safety switch and a pair of thermal actuators normally ofsaidactuators being heated upon-a call for burner operation to energizethe burner and to close a heating circuit for the second actuator.

e as the arrangement being such that when both the The control apparatusof the present inventhermal actuators are hot the safety switch istripped to open'position. A combustion responsive device is provided forthe purpose of deenergizing both actuators in the event that com-- 80bustion is established before the safety switch has been opened.

Other objects will readily become apparent to those who are skilled inthe art when the following specification is read in the light of the anaccompanying drawing in which:

\ Figure 1 is a more or less diagrammatic showingof a control systemembodying my invention,

Figure 2 is a detail view of the safety switch and two latches takenalong the line 2-2 of Figto are 1, and i ofstiflening 'ilanges l2 and I3extending longitu'dinaliy of the member H. -A pairof latches M and IIare mormted upon a rod I. carriedby v the flanges l2 and It at one endof the same member ll the arrangement being such that the are adapted torotate about 'therod ll. Seel'lgure-ii. Abiasing spring ll onnectedtheirame il andattheotherendtoamember ll which is flxedto the oppositeend ofthe Asecondbiaain'gspringflisconticularly important where thetiming means is tion it absorbs such a large quantity of heat that 1 itis apt to require an excessive time period to dool 0E and return to itscold position followat one end to the latch it below" also to a secondfixed member 2 5 connected to frame ll directly in back of member is asseen in Figure l. A portion of spring it may be seen in the detail viewshown in Figure 2. The two sprin s 88 and 26) therefore bias thelatches, i l and it; for rotation in a clockwise direction as seen inFigure 1. The latch 85 is actually direetly be n the latch isles seen inFigure l. The latch 5 and member 26 are shown to extend slightly abovelatch is and member is respectively in Figure 1. They have been shownthis way for the sake of. clarity only, as they are preferably of thesame size.

A thermally expansible wire 22 is connected a one end to the latch iiijust above the frame ii, and at its other end to thefixed member 6 9.Thus it can readily be seen that the biasing spring l8 maintains theexpansible wire 22 under tension and that upon expansion of the wire 22the latch l will rotate in a clockwise direction and upon contraction ofthis wire the latch will be rotated in a counter-cloclswise direction. Asecond expansible wire 23 is connected at one end to the latch it justabove the frame ii and at its 0D- posite end to the second fixed member2 5. The biasing spring. so will maintain the expansible nected to thelatch it below the frame ii and border. Therefore the reference numeralill in dicates the usual oil burner motor and the reierence humeral :32indicates any of the usual types of-electric ignition devices forigniting the oil delivered to the burner by the motor 435.

The combustion responsive device has been indicated diagrammatically at63 as comprising a switch arm t8 which is adapted to engage a coldcontact 650: in the absence of combustion and at a hot contact iber inthe presence of combustion. Although various types oi. condition re--sponsive devices may be utilized successfully in I cember '2, L943. 7

this invention, I prefer to utilize the device which ant heat responsivedevice" and filed December 22, 1941, now Patent No. 2,336,399,-issued'Dclihis system may be controlled manually or may be controlled by anyautomatic control device which responds to a demand for burner operation. However for the purposes of the present wire 23 under tension, andas in the case of the a wire 22, expansion of the wire 2%) will cause arotation of latch is in a clockwise direction whereas a contraction ofthe wire 23 will cause rotation of the latch 85 in a counter-clockwisedirection. The two wires 22 and 23 preferably, al-' safety switch blade25 will be resting upon the tip of the insulating portions 26 and 27which are carried by the two latches it and i5 respectively. When theswitch blade 25 is in this position it will be in engagement with itstationary contact '28, or in other words the safety switch will belatched in closed position.

The latch id is provided with a portion so which extends horizontallybeneath the frame H and which carries pivotally a rod 3| having twoswitch I actuating portions 32 and 33. When the expansible wire 22 iscold as shownin Figure l the-rod 3i willnbe in its lowermost position atwhich.

time the switch actuating member Siw'illengage the two resilient switchblades 34 and 35 and hold them out of engagement with the switch. blades36 and .31. When the wire 22' expands and;

permits clockwise rotation of the latch I the" disclosure I have shownthe usual type of room thermostat in the form of a bimetallic element 65which is fixedat one end and which carries 7 contactld and then at aslightly lower temper-,

ature the contact blade 61? engages its stationary contact 39.

The control'system includes an electric relay which is shown ascomprising a winding 50 and an armature indicated by the dotted line tiwhich, when the winding so is deenergized, occu= pics the position shownin Figure 1 in which the two switch arms 62 and 6d are in open circuitposition and the switch arm 83 is in engagement with its out contact 65.Upon energization of the winding so the armature 60 will move to theleft at which time the switch arms 62, 63, and

it will be in engagement with their stationary all rod 3| will be raisedand will first permit thetwo switch blades Hand 35 to move as a resultoi. I

their own bias into engagement with the switch blades 38 and 3'!respectively. Further upward movement of therod.3l will cause the switchac-,

t'uating member 32% engage the resilient-switchergized the burner motorand ignition devices will blade 38 andmove it into engagement with theswitch blade 39. The function or these various:

switches will be explained in detail later inconnection with theoperation of the systemes a v whole;

i The .present bontrol systemv may be adapted contacts 56, El and 5drespectively. p

The electrical power is supplied to the system from the supply lines lidand H which feed the P imary winding E2 of a step-down transformerlshgving a low voltage secondary winding l4.

' Operation maintain the safety switch arm 25 in closed circult positionand all of the switchesicontrolled by the actuating rod 3i will be inopen'oircuit position. The relay winding 50 will be deenergized and'thecombustion responsive switch arm will be in engagement with its coldcontact a. Inasmuch as the relay winding is deenalso be deenergiz'ed.

Inasmuch as no heat is being supplied by the burner at this time, thetemperature at the thermostat 45 will begin to decrease and the thermo-'Stat I! will begin to decrease and the thermostat will cause theflexible switch arm-46 to move into engagement with the stationarycontact 48; No

circuit will be established at this time in'view of the fact that therelayarm is in its "out" position. The temperature at the thermostat 45will therefore continue to decrease until the blade 41 is moved intoengagement with the stationary contact 49. This will establish anenergizing circuit for the expansible wire 22 which extends from oneside of the secondary winding I3 of the transformer 13 through conductorI8, safetyswitch arm 25, contact 28, conductor TI, contact 48, switchblades 46 and 41, contact 49, conductors I8, I9. 80 and BI, contact 85,switch arm 63, conductors 82, 83 and 84, combustion responsive switcharm 44, cold contact 45a, conductor 85, expansible wire 22 and conductor85 back to the other side of the secondary winding 14.

The establishment of the above circuit causes sufficient heating of thewire 22, due to its own resistance, to cause it to expand and permitrotation of the latch I4 in a clockwise direction as seen in Figure 1.Such rotation causes the actuating rod 3| to move upwardly and permitmovement of the resilient contact blades 34 and 35 to closed circuitposition. The switch blade 34 is in circuit with the ignition device 42and in view of the fact that the switch arm 62 is still in open circuitposition the movement of the switch blade 34 into engagement with theswitch blade 36 will not result in the establishment of a circuit .atthis time. The movement of the switch blade expansible wire 23 iseffectively shunted out by I means of the switch arm 83 and contact 85.Thus safety switch without putting undue strain upon the operatingmechanism of the switch. These details have not been illustrated in thisapplication which has been limited more or less to a diagrammaticshowing.

The second result is accomplished by the move" ment of the relay switcharms 32, 63 and 3:3 into engagement with their stationary contacts 5 3,iii and 88 respectively. Movement of the switch arm 64 into engagementwith contact 68 establishes a shunt circuit around the switch formed bythe contact blade 4! and contact 49. This circuit extends through theswitch blade 46, bimetal 45, conductor. 98, switch arm 64, contact 38and conductors 99, 88 and I9. Thus when the switch arm 84 has been movedto closed circuit position a holding circuit is set up to maintainoperation of the system even though the temperature at the thermostatmay rise sufiiciently to cause the switch blade 41 to separate fromcontact 49.

Movement of the switch arm 63 into its at tracted position first causesit to separate from the contact 65 thereby breaking the originalenergizing circuit for the expansible wire 22. This wire however remainsenergized at this time by a circuit which extends from one side of thesecondary winding I4 through conductor 16, safety switch arm 25, contact28, conductor ll, contact 48, switch blade 46, bimetal thermostat 45,conductor 98, switch arm 64, contact 68, conductors 99, 88, I9 and 88,expansible wire 23, conductor no control action will take place untilthe actuating member 3I causes a movement of the resilient contact blade38 into engagement with the contact blade 39. This establishes a circuitfor 1 the relay winding 5|! which extends from one side of the secondarywinding I4 through conductor 15, safety switch arm 25, contact 28,conductor TI, contact 48, switch blades 46 and 41, contact 49,conductors I8 and 88, expansible wire 23, conductor 89, switch blades 31and 35, conductors 90, 83 and 92, switch blades 38 and 39, conductors 93and 94, relay winding 50, and conductor 35 back to the other side of thesecondary winding 14.

Closure of the above circuit accomplishes two important results. Inthe'first place it energizes relay 58 and breaks the shunt around theexpansible wire 23 and starts this wire heating and expanding. It willbe noted that the expansible wire 22 is already in its heated state andtherefore it has rotated the latch I4 from beneath the safety switch arm25, but this arm remains in its latched position due to the latch I5.Heating of the wire 23, however will cause the latch I5 to start torotate in a clockwise direction and if this action is permitted tocontinue for a predetermined length of time, usually about 90 seconds,the latch I5 will move from beneath the safety switch arm 25 and permitit to move to open circuit position as shown in Figure 3. At this timethe arm 25 drops down out of engagement with its contact 28 and intoengagement with a stop 97. The opening of the safety switch removes thepower from the entire low voltage portion of the system and thereforedeenergizes both of the expansible wires 22 and 23 as well as the relaywinding 58. The safety switch must be reset manually and if desired maybe provided with the usual trip free reset which is now common in theart. In actual practice some strain release means would probably beprovided between the latches I4 and I5 and the safety switch arm 25 topermit the expansible wires 22 and 23 to cool ofi and contract followingthe opening of the 89, switch blades 37 and 35, conductors 99, 83. 84,combustion responsive arm 44, cold contact 45a, conductor 85, expansiblewire 22 and oohductor 88 back to the other side of the secondary winding14. Therefore after the relay winding 50 has been energized theexpansible wire 22 and the relay winding 50 are connected in paralleland they are each connected in series with the expansible wire 23. Notethere is less current flowing through the expansible wire 22 at thistime, however this current is suihcient to maintain this wire in itsheated condition so that the latch I4 will be rotated sufiiciently topermit the safety switch arm 25 to drop to the position shown in Figure3 should the expansible wire 23 heat for a suflicient period of time torotate the latch I5 from beneaththe switch arm 25.

Movement of the relay switch arm 32 into engagement with contact willresult in the es tablishment of a circuit for energizing both burnermotor 4i and the ignition device 52. This circuit extends from thesupply line 7! through conductor ICII, contact 65, switch arm conductors I82 and I03, burner motor 4i and conductor I94 back to the othersupply line l I. The ignition device 42 is energized by means or" acircuit extending from the supply line It through conductor I Hi,contact 86, switch arm 62, conductors I82 and H15, switch blades 34 and3t, conductor I08, ignition device 42 and conductor I81 back to theother supply line ii.

If combustion is not established within a predetermined period of timethe expansible wire 23 will heat sufficiently to,release the safetyswitch arm 25 as described above. This will cut off the power to the lowvoltage portion of the system and the safety switch will have to bemanually reset in order to restart the system. Normally, however, theenergization of v burner motor 4| and ignition device 42 will sultin'the establishment of combustion which will cause the combustionresponsive switch arm 44 to move from engagement with its cold contact45a into engagement with its hot contact of the secondary winding 14.

46a. This action will break the circuit through the expansible wire 22and will establish a holding circuit for the relay winding 59 which isindependent of any of the switches operated by asraave of the combustionresponsive switch arm 44 with 46, bimetallic element 45, conductor 99,switch.

arm 64, contact 68, conductors 99, 80 and I09,

hot contact 46a, combustion responsive switch arm 44, conductors 84, 83,82, switch arm 63, contact 61, conductors H0 and" 94, relay winding 50and conductor 95 back to the other side Theexpansible wire 22 will nowstart coo and contracting in view of the fact that the circuittherethrough has been broken. This will cause the switch actuating rod3| to move downwardly first permitting the switch blade 38 to move outof engagement with the switch blade 39. This will have no effect uponthe system in view of the fact that a holding circuit for the relaywinding 50 has been established independently of this switch. Furthermovement of the actuating rod 3| will cause the switch blade 35 to moveout of engagement with the switch blade 3?. This action will break thecircuit through the expansible wire 23. It is pointed out how ever thatthis wirewas effectively deenergized at the time that the combustionresponsive switch arm 44 engaged the hot contact 46a 7 because theclosure of this switch established a shunt around the expansible wire 23which extends from one side thereofthrough conductors 88, 19, and I09,hot contact 48a, combustion responsive switch arm 44, conductors 84, 83and 99,

switch blades 35 and 31, and conductor 89 to the other side of hot wire23. Thus the separation of the switch blade 35 from the blade 31 has Ano effect upon the system.

The lowering of the actuating rod 3| also causesthe switch blade 34 toseparate from the switch blade 35. It will be noted that these twoblades are in the circuit to the ignition device 42 and therefore theirseparation will terminate operation of the ignition device. The circuitto the burner-motor 4| however is independent of.

this switch and therefore will continue in operation as long asthe'relay winding 59 is energized.

The above is'the running condition of thesystem. It will be noted thatas soon as combustion i established both of the expansible wires 22 and23 are effectively deenergized and will start contractingto prevent theopening of the safety switch. However the ignition switch 34, 36 willremain closed and the ignition device energized until the expansiblewire 22 has cooled sumciently to open the switch 34, 35. This providesfor a proper post ignition period which is very desirable in the usual'oil burner control system. It will benoted thatthe running circuit forthe system passes serially through the thermostatic switch 48, 45, thecombustionresponsive switch 46, 44 and a holding switchwhich was closedby momentary power failure, a flame failure, or an increase intemperature of-the roomj thermostat 45 will cause the relay to 'bedeenergized. In the event of a flame failure or a momentary powerfailure the original energizing circuit for the expansible wire 22 willbe substantially immediately reclosed by engagement of the relay switcharm 93 with its out contact sand engagement motor 4| and ignition device42 until the expansible wire 22 has heated sufliciently to causemovement of the switch blade 38 into engagement with the switch blade39. The time required for the expansible wire 22 to produce this actionis sufficient to permit any unbiirned vapors which might cause anexplosion to pass out of the combustion chamber and up the stack. Inother words the expansible wire 22 times the delay between successiveburner energizations.

As many changes and modifications of this invention will undoubtedlyoccur to" those who are skilled in the art I wish it to be understoodthat I intend to be limited, not by the specific disclosure embodiedherein, but only by the scope of the accompanying claims.

I claim as my invention:

1. A fluid fuel burner control system comprising in combination, fueldelivery means, means for igniting said fuel, a timer, a main switch, asafety switch in control of said fuel delivery and said igniting means,electrical timing means for opening said safety switch at the end of atimed interval, an energizing circuit for said timer controlled by saidmain switch, means operated by said timer when energized for renderingsaid fuel delivery means operative to deliverafuel and for energizingsaid igniting means and'electrical tim- "ing means for said safetyswitch, and means op- 'erating in response to combustion fordeenerinterval, an energizing circuit for said timer controlled by saidmain switch, means operated by said timer when energized for renderingsaid fuel delivery means operative to deliver fuel and for energizingsaid igniting means and electrical timing means for said safety switch,means operating inresponse to combustion for deenergizing said timer andelectrical timing means and maintaining said fuel delivery meansoperative independently of said timer, and means operated by said timerupon cooling for deenergizing said igniting means. I I

3. A fluid fuel burner control system comprising in combination, fueldelivery means, means for igniting said fuel, a timer, a main switch, asafetyswitch in control of said fuel delivery and said igniting means,electrical timing meansfoi opening said safety switch at the end of atimed interval, hot and cold combustion responsive switches, anenergizing circuit for said timer indelivery means operative and forenergizing sail i niting means, a relay switch closed by said elay whenenergized, said cold combustion responsiye switch opening upon theestablishment o:

' switches/a relay, a first relay switch which is closed by said timerwhen energized, an energizing circuit for said relay including said mainswitch, electrical timing means, and first timer switch, means operatedby said relay for rendering said fuel delivery means operative and forenergizing said igniting means, means for opening prising incombination; fuel delivery means; a

heaters; means for closing said further switch said cold combustionresponsive switch and closing said hot combustion responsive switch uponthe establishment of combustion, a second relay switch which is closedby said relay when ener gized, a holding circuit for said relayincluding said main switch, hot combustion responsive switch and secondrelay switch, said last named holding circuit being connected in shuntwith said electrical timing means for effectively deenergiz ing thesame, and means operated by said timer upon deenergization thereof fordeenergizing said igniting means.

10. A fluid fuel burner control system compris.. ing in combination,fuel delivery means, means for igniting said fuel, a timer, a mainswitch, a

safety switch in control of said fuel delivery and said igniting means,electrical timing means for opening said safety switch at the end of atimed interval, hot and cold combustion responsive switches, a relay, afirst relay switch which is closed when said relay is deenergized, anenergizing circuit for said timer including said main switch, firstrelay switch, and cold combustion responsive switch, a first timerswitch which is closed by said timer when energized, an energizingcircuit for said relay including said main switch, electrical timingmeans, and first timer switch, means operated by said relay forrendering said fuel delivery means operative and for means uponenergization of said one heater;

means effective upon closure of said further switch means to establishenergizing'circuits to said fuel delivery means and said other heater;and means including a combustion responsive device for deenergizing bothof said heaters while establishing a running circuit to said fueldelivery means independent of said further switch means so that upon thecooling of said heaters and the resultant opening of said further switchmeans, said fuel delivery means remains in operation.

13. In a fluid fuel burner control system comprising in combination;fuel delivery means; means for igniting said fuel; a safety switch incontrol of said fuel delivery means; means including a pair of heatersefiective only when both of said heaters are energized to cause openingof said safety switch; a further switch means; means for energizing oneof said heaters; means for closing said further switch means uponenergization of said one heater; means efiective upon closure of saidfurther switch means to establish energizing circuits to said fueldelivery means, said igniting means, and said other heater; and meansincluding a combustion responsive device for deenergizing both of saidheaters while establishing a running circuit to said fuel delivery meansindependent of said further switch means so that upon the cooling ofsaid heaters and the resultant opening of said further switch means,only said fuel delivery means remains in energizing said igniting means,means for opening said cold combustion responsive switch and closingsaid hot combustion responsive switch upon the establishment ofcombustioma second relay switch which is closed by said relay whenenergized, a holding circuit for said relay includ ing said main switch,hot combustion responsive switch and second relay switch, said lastnamed.

holding circuit being connected in shunt with saidelectrical timingmeans for effectivehr deenergizing the same, switch means in series withsaid electrical timing means opened by said timer upon deenergizationthereof for breaking the circuit through said electrical timing means,and means operated by said timer upon deenergization thereof fordeenergizing said igniting means.

11, A fluid burner control system comprising in combination, fueldelivery means, a biased open operation.

14. In fluid fuel burner control-apparatus for controlling a fueldelivery means; a safety switch adapted to control said fuel deliverymeans; means including a pair of heaters effective only when both ofsaid heaters are energized to cause opening of said safety switcm'afurther switch means; means for closing said further switch means uponenergization of said one heater; circuit means including said switchmeans and said other heater and adapted to be associated with a fueldelivery controlling means in such a manher as to establish, uponclosure of said further switch means, energizing circuits to said fueldelivery means and said other heater; and further circuit means adaptedto be connected to a combustion responsive device and to said fuel de=livery controlling means for deenergizing both safety switch in controlof saidfuel delivery means, first and second latches for maintainingsaid safety switch closed, first and second thermal actuators for saidlatches, said actuators, when heated, moving said latches in a directiomto release said safety switch for movement to open position, means forclosing a, heating circuit for said first actuator in response to ademand for burner operation, means controlled by said first actuator andeffective when said actuator is hot to render said fuel delivery meansoperative to deliver fuel and ti} establish a heating circuit for saidsecond actuator, and means operating in response to the establishment ofcombustion for opening both of saidheating' circuits while maintainingoperation of said fuel delivery means.

of said heaters upon theestablishment of combustion while establishing arunning circuit to said fuel delivery means independent of said furtherswitch means.

15.. Fluid fuel burner control apparatus for a fuel delivery means andmeans for igniting said fuel, a timer, means including a safety switchadaptedto be connected to said fuel delivery means and said ignitingmeans for controlling the same, electrical timing means foropening saidsafety switch at the end of a timed interval, circuit means adapted tobe connected to a main switch and to constitute when so connected anenergizing circuit for said timer controlled by said main switch,further circuit means including said electrical timing means for saidsafety switch and-a switch operated by said timer, said further circuitmeans being adaptedto be connected to said fuel delivery means and saidigniting means and effective when 50 connected to render said fueldelivery means operative to deliver fuel and to energize said ignitionmeans and electrical timing means for said safety switch, meansincluding said timer and electrical timing means and adapted in be-s0nnected to a device respnm we to summation and 30 said iuei daliverymeans for deenergizing said timer and electrical timing G. ISSERSTEDT.

